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Heat Mat for Mushroom Grow Kits
A heat mat for a mushroom grow kit is a low-wattage heating pad that sits under the kit and keeps it at the steady 23–25 °C that Psilocybe cubensis prefers when your room runs cooler. Our mycelium heat mat comes in 5 W and 7 W, each with an adjustable controller, and is always used with a silicone heat guard between mat and kit.
When a grow kit needs a heat mat
Most homes run cooler than people think. Floors, windowsills and rooms that cool down at night often sit below 23 °C, especially from autumn to spring. A kit kept too cool does not die, but it slows down, and a slow kit gives contaminants more time. If your room holds 23–25 °C by itself, you do not need a mat. In a warm summer room that already gets close to 27 °C, a mat only adds risk. A thermometer strip on the kit tells you which situation you are in.
5 W or 7 W: which heat mat do you need?
The wattage follows the size of what you are heating. More substrate needs a little more output to reach the same temperature; a stronger mat does not make a small kit grow faster.
| Product | Volume | Heat mat |
|---|---|---|
| Medium grow kit | 750 cc | 5 W |
| Large grow kit, including all special strains | 1200 cc | 7 W |
| Extra Large grow kit | 2100 cc | 7 W |
| Ready-to-Grow Bag XL | one size | 7 W |
Setting it up the right way
Start once the kit is soaked, drained and sealed in its filter bag. Build the stack from the bottom up: heat mat, silicone heat guard, then the kit or grow bag. Never place a kit directly on the mat; the base can heat far beyond 27 °C while the rest of the kit still feels fine.
The controller sets the output, not a target temperature. As a starting point, the Heat Mat & Heat Guard Manual suggests a quarter to half for the smaller kit and half to maximum for the larger sizes. After a few hours, read an adhesive thermometer strip on the side of the kit and turn the knob up or down until it settles at 23–25 °C. Recheck when the weather changes, because the same setting gives a different result in a warmer room.
Place the setup on a flat, stable surface out of direct sunlight, and keep the cable clear of water when you add the 150 ml to the bag. For more on keeping kits warm when the heating is off at night, read keeping your kit warm in winter.
Frequently asked questions
What temperature should a heat mat keep my grow kit at?
Aim for a steady 23–25 °C at the kit and keep it below 27 °C. The heat mat has no thermostat, so the controller only changes how much heat it gives off. Measure at the kit with a thermometer strip and adjust the knob until the reading is stable.
Which heat mat do I need for a 1200 cc grow kit?
The 7 W heat mat. It is also the right choice for the Extra Large 2100 cc kit and the Ready-to-Grow Bag XL. The 5 W version is meant for the Medium 750 cc kit.
Can I put my grow kit directly on the heat mat?
No. Direct contact creates hot spots at the base of the kit that can stress or kill the mycelium. Always place a silicone heat guard between the mat and the kit so the warmth spreads evenly.
Does a heat mat make mushrooms grow faster?
A heat mat brings a cool kit up to its preferred range; it does not push growth beyond it. Above 27 °C the kit gets stressed rather than faster. Steady warmth matters more than extra warmth.
Can I leave the heat mat on day and night?
Yes, as long as the kit stays at 23–25 °C. A steady temperature is the point of using a mat. If the room warms up during the day or in a warm spell, turn the controller down or switch the mat off.
